How does the food change in consistency and form?
The food we eat changes in consistency and form due to digestion. First, when we ingest or take in the food into the mouth, its physical breakdown starts, breaking it into smaller particles. While chewing, the food is mixed with salivary amylase (saliva), chemically digesting it, and breaking down starch into maltose. It is then sent to the stomach through the pharynx and the esophagus. The muscle layers of the stomach wall compress the food, mixing it with gastric juice, and subsequently forming semifluid chyme. The partially digested food is then sent to the small and large intestines, fully digesting the food, and forming feces in the process.
How could the body absorb the nutrients from the foods we eat?
The major site of absorption of nutrients and water is the small intestine as it absorbs 90% of nutrients and water. The small intestine contains absorptive cells, villi, and microvilli, which all contribute to the absorption of nutrients. On the other hand, the large intestine absorbs the remaining water, ions, and vitamins through its mucosa.
Source:
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy & physiology. Fifteenth edition; Wiley Loose-Leaf Print Companion. Hoboken, New Jersey, John Wiley & Sons, Inc.